ADV7180
INTRODUCTION
The ADV7180 is a versatile one-chip multiformat video
decoder that automatically detects and converts PAL, NTSC,
and SECAM standards in the form of composite, S-video, and
component video into a digital ITU-R BT.656 format.
STANDARD DEFINITION PROCESSOR
The ADV7180 is capable of decoding a large selection of
baseband video signals in composite, S-video, and component
formats. The video standards supported by the video processor
include PAL B/D/I/G/H, PAL 60, PAL M, PAL N, PAL Nc,
NTSC M/J, NTSC 4.43, and SECAM B/D/G/K/L. The
ADV7180 can automatically detect the video standard and
process it accordingly.
The simple digital output interface connects gluelessly to a wide
range of MPEG encoders, codecs, mobile video processors, and
Analog Devides digital video encoders, such as the ADV7179.
External HS, VS, and FIELD signals provide timing references
for LCD controllers and other video ASICs that do not support
the ITU-R BT.656 interface standard.
The ADV7180 has a 5-line, superadaptive, 2D comb filter that
gives superior chrominance and luminance separation when
decoding a composite video signal. This highly adaptive filter
automatically adjusts its processing mode according to the
video standard and signal quality without requiring user
intervention. Video user controls such as brightness, contrast,
saturation, and hue are also available with the ADV7180.
ANALOG FRONT END
The ADV7180 analog front end comprises a single high speed,
10-bit, analog-to-digital converter (ADC) that digitizes the
analog video signal before applying it to the standard definition
processor. The analog front end employs differential channels
to the ADC to ensure high performance in mixed-signal
applications.
The ADV7180 implements a patented Adaptive Digital Line
Length Tracking (ADLLT) algorithm to track varying video line
lengths from sources such as a VCR. ADLLT enables the
ADV7180 to track and decode poor quality video sources such
as VCRs and noisy sources from tuner outputs, VCD players,
and camcorders. The ADV7180 contains a chroma transient
improvement (CTI) processor that sharpens the edge rate of
chroma transitions, resulting in sharper vertical transitions.
The front end also includes a 3-channel input mux that enables
multiple composite video signals to be applied to the ADV7180.
Current clamps are positioned in front of the ADC to ensure
that the video signal remains within the range of the converter.
A resistor divider network is required before each analog input
channel to ensure that the input signal is kept within the range
of the ADC (see Figure 24). Fine clamping of the video signal
is performed downstream by digital fine clamping within
the ADV7180.
The video processor can process a variety of VBI data services,
such as closed captioning (CCAP), wide-screen signaling
(WSS), copy generation management system (CGMS), EDTV,
Gemstar® 1×/2×, and extended data service (XDS). Teletext data
slicing for world standard teletext (WST), along with program
delivery control (PDC) and video programming service (VPS),
are provided. Data is transmitted via the 8-bit video output port
as ancillary data packets (ANC). The ADV7180 is fully
Macrovision certified; detection circuitry enables Type I,
Type II, and Type III protection levels to be identified and
reported to the user. The decoder is also fully robust to all
Macrovision signal inputs.
Table 1 shows the three ADC clocking rates, which are determined
by the video input format to be processed—that is, INSEL[3:0].
These clock rates ensure 4× oversampling per channel for CVBS
mode and 2× oversampling per channel for Y/C and YPrPb modes.
Table 1. ADC Clock Rates
Oversampling
Rate per Channel
Input Format
CVBS
Y/C (S-Video) 2
ADC Clock Rate1
57.27 MHz
86 MHz
4×
2×
2×
YPrPb
86 MHz
1 Based on a 28.6363 MHz crystal between the XTAL and XTAL1 pins.
2 Refer to INSEL[3:0] in Table 103 for the mandatory write for Y/C (S-video) mode.
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